TY - JOUR

T1 - Evolutionary success in arid habitats

T2 - Morpho-anatomy of succulent leaves of Crassula species from southern Africa

AU - Fradera-Soler, Marc

AU - Rudall, Paula J.

AU - Prychid, Christina J.

AU - Grace, Olwen M.

PY - 2021

Y1 - 2021

N2 - Succulence is widely interpreted as an adaptation to drought, usually associated with CAM and xeromorphic features among arid-adapted plants. However, this syndrome can also be observed in species typical of mesic and even hydric environments. The leaf-succulent genus Crassula (Crassulaceae) occurs in contrasting habitats in all nine biomes of southern Africa. This study represents the first to compare leaf traits in Crassula species which in nature are confined to diverse habitats in southern Africa. To determine their potential adaptive significance, we investigated leaf succulence and several morpho-anatomical traits of five southern African Crassula species (C. ausensis, C. brevifolia, C. multicava, C. nudicaulis, C. tecta), which occur naturally in habitats of differing aridity; all plants were grown under glasshouse conditions. For each species, we recorded water content, leaf anatomy, and leaf surface structure and hydrophobicity. We found that water content is relatively consistent in Crassula regardless of natural habitat. In contrast, most leaf morpho-anatomical traits examined here are related to macroclimatic conditions. We hypothesize that differences in mesophyll traits in Crassula are potentially linked to water storage and CAM performance, while differences in leaf surface properties are more closely related to water conservation and probably also to water uptake through hydathodes.

AB - Succulence is widely interpreted as an adaptation to drought, usually associated with CAM and xeromorphic features among arid-adapted plants. However, this syndrome can also be observed in species typical of mesic and even hydric environments. The leaf-succulent genus Crassula (Crassulaceae) occurs in contrasting habitats in all nine biomes of southern Africa. This study represents the first to compare leaf traits in Crassula species which in nature are confined to diverse habitats in southern Africa. To determine their potential adaptive significance, we investigated leaf succulence and several morpho-anatomical traits of five southern African Crassula species (C. ausensis, C. brevifolia, C. multicava, C. nudicaulis, C. tecta), which occur naturally in habitats of differing aridity; all plants were grown under glasshouse conditions. For each species, we recorded water content, leaf anatomy, and leaf surface structure and hydrophobicity. We found that water content is relatively consistent in Crassula regardless of natural habitat. In contrast, most leaf morpho-anatomical traits examined here are related to macroclimatic conditions. We hypothesize that differences in mesophyll traits in Crassula are potentially linked to water storage and CAM performance, while differences in leaf surface properties are more closely related to water conservation and probably also to water uptake through hydathodes.

KW - Crassula

KW - Drought adaptation

KW - Ecology

KW - Leaf anatomy

KW - Succulent plants

KW - Xeric habitats

KW - LEAF ANATOMY

KW - DESERT

KW - NAMAQUALAND

KW - CONSTRAINTS

KW - STRATEGIES

KW - HYDATHODES

KW - PLANTS

KW - FOG

U2 - 10.1016/j.jaridenv.2020.104319

DO - 10.1016/j.jaridenv.2020.104319

M3 - Journal article

VL - 185

JO - Journal of Arid Environments

JF - Journal of Arid Environments

SN - 0140-1963

M1 - 104319

ER -